Semiconductor device and method for fabricating same

ABSTRACT

A top surface of a LSI chip having a structure of a bare chip is provided with bumps, and a protective resin is provided for at least side surfaces of the LSI chips. The LSI chip is prevented from being chipped off or cracked because of protective resin provided for the side surfaces of the LSI chip. The invention provides a semiconductor device and a method for fabricating the same, in which the chip or a package thereof is prevented from being damaged, and thereby yield rate of the semiconductor device can be heightened. Since the numbers of the parts of the semiconductor device and the steps of using jigs and tools necessary for the fabrication process are reduced, fabricating cost of the semiconductor device can be cut down.

FIELD OF THE INVENTION

[0001] The invention relates to a semiconductor device and a method forfabricating the same, and especially to a semiconductor device in whicha bare chip is coated with protective resin and prevented from beingcracked and a method for fabricating the same.

BACKGROUND OF THE INVENTION

[0002] Since a bare chip is provided with plural bumps serving aselectrodes on an obverse surface thereof and not coated with protectiveresin, a space necessary for mounting it is small. Accordingly, the barechip is suited for an electronic instrument in which the space foraccommodating parts is limited, such as a portable telephone.

[0003]FIG. 1 shows a conventional semiconductor device (a bare chip).

[0004] An insulating layer 102 is provided for an obverse surface of aLSI chip 1, and a wiring layer 104 having LSI electrodes 103 thereon isformed on the insulating layer 102. Plural bumps 105 serving as externalelectrodes are mounted on leading ends of the LSI electrodes 103 formedon a circuit area 106.

[0005]FIG. 2 shows the steps of a process for fabricating theconventional semiconductor device shown in FIG. 1.

[0006]FIG. 3A shows a plan view of the wafer, which is not yet dicedinto the bare chips. FIG. 3B shows a cross-sectional view of the barechip. FIG. 3A corresponds to a prior treatment of the step 201. Thesteps of the fabrication process ranging from dicing to mounting will beexplained referring to FIGS. 2, 3A, 3B. “S” in FIG. 2 means the step.

[0007] As shown in FIG. 3A, the wafer is diced along boundary lines(broken lines) between the LSI chips 101, and the individuatedsemiconductor devices (the bare chips) 100 are obtained. After the waferis diced into the semiconductor device 100 (S 201), the semiconductordevices of a predetermined number are transferred to a tray (S 202).Each semiconductor device 100 in the tray is supported by a jig on theinside of a crack permissible areas 107 so that circuit surfaces and thebumps 105 are not brought into contact with the tray, wherein the crackpermissible area means a frame-shaped region ranging from edges of theLSI chip 101 to exterior electrodes on the same, and a width thereof isabout 50 μm. The tray is carried to the step of inspecting thesemiconductor devices by means of a transportation jig for exclusive use(S 203). After the step of inspecting the semiconductor devices 100 isover (S204), the semiconductor devices 100 are again transferred to thetray (S205), carried to the step of packing the semiconductor devices100, and packed up (S206). Thereafter, the package is transported to theuser (S 207). The user opens the package delivered in this way (S 208),transfers the semiconductor devices to a transportation jig (S 209),mounts the semiconductor devices 100 on a printed circuit board by meansof a pickup tool, and connects the bumps 105 with wirings by reflowsoldering (S210).

[0008] However, according to the aforementioned semiconductor devices,since the individuated semiconductor devices are transferred to the trayand transported in condition that they are contained therein, there is apossibility that a shock may exert on the semiconductor devicespartically in case that they are brought into contact with the tray atthe time of transportation or the jig at the time of inspection. In sucha case, the semiconductor device is apt to be cracked or broken off, andthe electrodes or the circuit area may suffer the damage. Especially,the edges of the chip are apt to be cracked and broken off. Such adamage becomes a cause of deterioration of yield rate of products orquality of the forwarded semiconductor devices.

SUMMARY OF THE INVENTION

[0009] Accordingly, it is an object of the invention to provide asemiconductor device and a method for fabricating the same, in which asemiconductor device is prevented from being cracked, yield rate thereofis improved, and quality of forwarded products is guaranteed.

[0010] According to the first feature of the invention, thesemiconductor device comprises:

[0011] a bare chip fabricated as a large scale integrated circuit,

[0012] plural bumps provided for an obverse surface of the bare chip,and

[0013] protective members formed on at least side surfaces of the barechip.

[0014] According to the aforementioned structure, a protective memberprovided for at least side surfaces of a bare chip reduces an externalforce exerted on a chip, and especially prevents corners of a chip frombeing cracked or broken off. As a result, defects occurring at the timeof transportation or mounting, imperfections in joints occurring at thetime of mounting, etc. are reduced, hence the semiconductor device canbe small-sized and reliability thereof can be heightened.

[0015] According to the second feature of the invention, a method forfabricating the semiconductor device comprises the steps of:

[0016] sticking a wafer on which plural bumps are formed to an adhesivesheet,

[0017] dicing the wafer into individuated chips so as not to dice theadhesive sheet,

[0018] forming spacings having predetermined widths between theindividuated chips stuck to the adhesive sheet,

[0019] coating the spacings formed between the individuated chips withresin,

[0020] hardening the resin to unify the individuated chips like a wafer,and

[0021] providing separate chips by dicing the unified chips alongboundary lines between the individuated chips.

[0022] According to the aforementioned method, since the wafer on whichplural bumps are formed is stuck to the adhesive sheet, it becomespossible to expand the adhesive sheet after the wafer is diced, andthereby the spacings between the chips which are wide enough to becoated with resin can be formed. When resin is hardened after thespacings are coated with resin, the chips unified like a wafer can beformed. The individuated chips, each of which is coated with resin atthe side surfaces thereof, can be obtained by dicing the unified chipsalong the boundary lines between the chips. Accordingly, since theseparated chips do not through the fabrication process, the steps ofhandling the chips can be eliminated, the number of the steps of usingjigs and tools is reduced, and a metallic mold used in the step ofmolding resin becomes unnecessary. Then, the method for fabricating thesemiconductor device is simplified. Moreover, since the LSI chip isprevented from being cracked by providing protective resin for the sidesurfaces thereof, reliability and yield rate of the products can beheightened. Stillmore, since the specific character of the bare chip ismaintained, the number of parts does not increase, the semiconductordevice can be small-sized, and cost thereof can be cut down.

[0023] According to the third feature of the invention, a method forfabricating the semiconductor device comprises the steps of:

[0024] sticking a wafer on which intermediate electrodes for mountingbumps thereon are arranged in accordance with a circuit pattern to anadhesive sheet,

[0025] dicing the wafer into individuated chips so as not to dice theadhesive sheet,

[0026] forming spacings between the individuated chips stuck to theadhesive sheet,

[0027] coating the spacings formed between the individuated chips and asurface of the wafer on which the intermediated electrodes are arrangedwith resin,

[0028] hardening the resin to unify the individuated chips like a wafer,

[0029] grinding an obverse surface of the unified chips to expose theintermediate electrodes, and

[0030] providing separate chips by dicing the unified chips alongboundary lines between the individuated chips.

[0031] According to the aforementioned method, the intermediateelectrodes formed on a circuit pattern on the wafer have function ofadjusting the height of the bumps above the chip surface and relaxingexternal forces exerting on the semiconductor device. Since the wafer onwhich the intermediate electrodes are formed is stuck to the adhesivesheet, the adhesive sheet can be expanded after the wafer is diced, andthe spacings, which are wide enough to be coated with protective resin,can be formed between the individuated chips. If the spacings are coatedwith protective resin which is hardened thereafter, the chip are unifiedlike a wafer. After the bumps are respectively mounted on theintermediate electrodes formed on the chips, the unified chips are dicedalong the boundary lines between the respective chips, and the separateLSI chips are completed. As mentioned in the above, since the separatechips do not pass through the fabrication process, the steps of handlingthe chips can be eliminated, the number of the steps of using jigs andtools is reduced, and the metallic mold used in the step of moldingbecomes unnecessary. Then, the fabrication process of the semiconductordevice is simplified. Moreover, since the LSI chip is prevented frombeing cracked by providing protective resin for the side surfaces andthe obverse surface of the LSI chip, reliability and yield rate of theproducts can be heightened. Stillmore, since the specific character ofthe bare chip is maintained, the number of parts does not increase, thesemiconductor device can be small-sized, and cost thereof can be cutdown.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention will be explained in more detail in conjunctionwith appended drawings, wherein:

[0033]FIG. 1 is a cross-sectional view for showing a conventionalsemiconductor device,

[0034]FIG. 2 is a flow chart for explaining the steps of fabricating abare chip shown in FIG. 1,

[0035]FIG. 3A is a plan view for showing a wafer before it is diced intobare chips,

[0036]FIG. 3B is a cross-sectional view of a bare chip diced from awafer shown in FIG. 3A,

[0037]FIGS. 4A to 4D are cross-sectional views for showing the first tofourth preferred embodiments of the invention,

[0038]FIGS. 5A, 5B are cross-sectional views for showing the fifth tosixth preferred embodiments of the invention,

[0039]FIG. 6 shows the steps of fabrication processes of semiconductordevices shown in FIGS. 4A, 4C.

[0040]FIG. 7 shows a method for thinning semiconductor devices shownFIGS. 4A, 4C,

[0041]FIG. 8 shows a method for fabricating a semiconductor device shownin FIG. 5A,

[0042]FIG. 9 shows a method for fabricating a semiconductor device shownin FIG. 4D,

[0043]FIG. 10 shows a method for fabricating a semiconductor deviceshown in FIG. 5B,

[0044]FIG. 11 shows a modification of a fabrication process shown inFIG. 9, and

[0045]FIG. 12 shows a result of comparison made between a percentdefective of semiconductor devices according to the invention and thatof conventional semiconductor devices.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] Hereafter, embodiments of the invention will be explainedreferring to the appended drawings.

[0047]FIGS. 4A to 4E show semiconductor devices according to the firstto fourth preferred embodiments of the invention.

[0048]FIG. 4A shows the semiconductor devices according to the firstpreferred embodiments of the invention. As shown in FIG. 4E, a main partof the semiconductor device is a square-shaped LSI chip (a bare chip) 1,and an obverse surface thereof is provided with plural LSI electrodes 2arranged two dimensionally at a predetermined pitch. A bump (a solderbump) 3 is mounted on each LSI electrode 2 so as to be connected withthe outside as shown in FIG. 4E. Each side surface of the LSI chip 1 iscoated with protective resin 4 having a predetermined thickness as shownin FIG. 4E. Resin of epoxy or silicone series having excellent adhesiveor thermal property is suited for protective resin 4. Since the sidesurfaces of the LSI chip 1 are coated with protective resin 4, edgesthereof are prevented from being damaged by a shock exerted thereon incase that the LSI chip 1 is inserted into or drawn out from a socket atthe time of inspection of the semiconductor device or carrier by amounter at the time of mounting. A thickness of protective resin 4 canbe selected at will in a range 0.005 mm to 1.0 mm. In FIG. 4A, it isselected to be 0.5 mm for instance.

[0049] In case that the bare chip is used as the LSI chip, it is apt tobe chipped off in a tray at the time of transportation or cracked at thetime of handling in a mounting instrument. However, according to theembodiment shown in FIG. 4A, since the side surfaces of the LSI chip 1is protected by protective resin 4, the LSI chip 1 is prevented frombeing chipped off or cracked. Moreover, since protective resin 4 isprovided for the LSI chip 1 only at the side surfaces thereof, amount ofresin can be reduced to the minimum, and a thin and small-sizedsemiconductor device can be obtained.

[0050] As mentioned in the above, according to the embodiment shown inFIG. 4A, since defects occurring at the time of transportation,imperfections in mounting or jointing, etc. in the fabrication processcan be reduced, yield rate and reliability of the products can beimproved. Moreover, since there is no necessity for using an interposer,such as a chip size package (CSP, hereinafter), the numbers of parts andthe steps of the fabrication process can be reduced, the semiconductordevice can be small-sized, and reliability thereof can be improved.

[0051]FIG. 4B shows the second preferred embodiment of the semiconductordevice according to the invention. The feature of the second preferredembodiment is that protective resin 5 is provided for a reverse surfaceof the LSI chip 1 in addition to the structure shown in FIG. 4A. As aresult, not only the side surfaces of the LSI chip 1 but also thereverse surface of the same can be protected from the outside. Thestrength of protective resin 4 is heightened by providing the protectiveresin 5. Moreover, when numerals for discrimination are stamped on thereverse surface of the semiconductor device, the stamped numerals can berecognized clearly. The thickness of protective resin 5 may be selectedat will in a range 0.001 to 1.0 mm. The thickness of protective resinmay be either the same as or different from that of the protective resin4.

[0052] According to the structure shown in FIG. 4B, yield rate andreliability of the semiconductor device can be further improved. Sincethere is no necessity for using the interposer, such as the CSP, in thiscase also, the numbers of the parts of the semiconductor device and thesteps of the fabrication process can be reduced.

[0053]FIG. 4C shows a semiconductor device according to the thirdpreferred embodiment of the invention. A feature of this embodiment isthat the obverse surface of the semiconductor device is coated withprotective resin 6 except areas on which the bumps 3 are mounted(bump-mounting areas, hereinafter) in addition to the structure shown inFIG. 4A. Since protective resin 6 protects a surface under which circuitpatterns are formed (a circuit surface, hereinafter) and fixes the bumps3 to the LSI electrodes 2, reliability of the semiconductor device canbe improved. The thickness of protective resin 6 may be selected at willin a range 0.005 to 0.5 mm, and the inventers confirm experimentallythat a satisfactory result can be obtained in case that protective resinis 0.02 mm thick.

[0054] Although the chip is frequently chipped off in a tray at the timeof transportation or cracked at the time of handling in a mountinginstrument in case that the bare chip is used as the LSI chip 1, thesedefects are reduced according to the semiconductor device shown in FIG.4C, because it is protected by protective resin 4,6. Moreover, thecircuit surface is protected against a mechanical shock exertingthereon, and the LSI electrode is prevented from being corroded bymoisture absorption by providing protective resin 6 for thesemiconductor device. As s result, according to this embodiment, sincecondemnations concerning the LSI chip 1, such as defects occurring inthe tray at the time of transportation, imperfections in mounting orjoint occurring at the time of fabrication, etc. can be reduced, yieldrate of the products can be heightened, and a moisture-resistingproperty of the semiconductor device can be improved. Moreover, sincethere is no necessity for providing an interposer, such as a CSP, thenumbers of parts and the steps of the fabrication process can bereduced.

[0055]FIG. 4D shows a semiconductor device according to the fourthpreferred embodiment of the invention. This embodiment combines thefeature of the structure shown in FIG. 4B with that of the structureshown in FIG. 4C. That is to say, the side surfaces of the LSI chip 1are coated with protective resin 4, the bump-mounting surface of thesame is coated with protective resin 6, and the reverse surface of thesame is coated with protective resin 5. Accordingly, in thesemiconductor device shown in FIG. 4D, all the surfaces of the LSI chip1, that is to say, the side surfaces, the reverse surface and thebump-mounting surface are protected from the outside. In addition tothat, since the moisture-resisting property of the LSI chip is improved,yield rate and reliability of the semiconductor device are furtherheightened. Moreover, the protective property of the semiconductordevice against the damage caused by a shock which is exerted on thesemiconductor device from a tool at the time of mounting or a socket atthe time of a test for selecting the chips. Then, the semiconductordevice can be treated as if an ordinarily packaged chip. Moreover, sincethe bumps 3 are reinforced, a value added of the semiconductor device isheightened. Since a interposer, such as a CSP, is not used, the numberof parts and the steps of the fabrication process can be reduced.

[0056]FIGS. 5A and 5B respectively show the semiconductor deviceaccording to the fifth and sixth preferred embodiments of the invention.

[0057]FIG. 5A shows the semiconductor device according to the fifthpreferred embodiment of the invention. The feature of this embodiment isthat it is provided with intermediate electrodes 7, each of which isinserted between the LSI electrode 2 and the bump 3 to combine them.Since the intermediate electrode 2 is provided for the LSI chip 1, aninterval between the LSI electrode 2 and the bump 3 can be adjusted, andthereby the bump 3 is prevented from being imperfectly connected with anexternal circuit. Moreover, since concentration of stress on a joint ofthe bump 3 is relaxed by the intermediate electrode 7, reliability ofthe joint between the bump and a printed circuit board can beheightened.

[0058] Since the semiconductor device is protected by protective resin4,6, the edges of the LSI chip 1 are prevented from being damaged orcracked in case that the semiconductor device is inserted into or drawnout from a socket at the time of inspection, or shocked by a mounter atthe time of a transfer in a mounting process. Moreover, since theintermediate electrode 7 is provided for the semiconductor device,stress 1 is relaxed and reliability of the joint of the bump 3 can beheightened. The thickness of the intermediate electrode 7 can beselected at will in a range 0.005 to 0.2 mm. As material of theintermediate electrode, not only Ni or Cu but also epoxy resincontaining filler formed of Ag are used. Ni or Cu is plated with Au inorder to increase wettability to the bump in most cases. When epoxyresin containing filler is used, Ni is put thereon, and Au is depositedon Ni.

[0059]FIG. 5B shows a semiconductor device according to the sixthpreferred embodiment of the invention. The feature of this embodiment isthat protective resin 5 is added to the reverse surface of the structureshown in FIG. 5A. Strength of protective resin 4 is heightened, becauseprotective resin 5 is provided for the LSI chip 1 similarly to thesemiconductor devices shown in FIGS. 4A, 4D. When reference numerals fordiscrimination is stamped on the reverse surface of the semiconductordevice, the stamped numerals can be recognized clearly. The thickness ofprotective resin 5 may be selected at will in a range 0.005 to 1.0 mm.The thickness of protective resin 5 may be either the same as ordifferent from that of protective resin 4. As explained in FIG. 5A,stress exerted on a joint from the outside is relaxed by providing theintermediate electrode 7, and reliability of the joint of the bumps canbe heightened.

[0060] Next, methods for fabricating the aforementioned semiconductordevices will be explained.

[0061]FIG. 6 shows the steps of the method for fabricating thesemiconductor devices shown in FIGS. 4A,4C.

[0062] The bumps 3 are previously formed on a wafer 10. The wafer 10adheres to the adhesive sheet 12, an adhesive property of which isdecreased by ultraviolet (UV) irradiation. Next, the adhesive sheet 12is fixed to a fixing ring 11 as shown in the step (a) in FIG. 6 (FIG.6(a), hereinafter similarly to the other steps of the respective methodsmentioned later.) In this condition, only the wafer 10 is diced withoutdicing the adhesive sheet 12, and individuated into plural LSI chips 1having predetermined dimensions.

[0063] Moreover, as shown in FIG. 6(c), after a ring-shaped expandingjig 13 is situated at a predetermined position which is near and lowerthan the fixing ring 11 for fixing the adhesive sheet 12, the expandingjig 13 is pushed up to expand the adhesive sheet 12 and extend spacingsbetween the LSI chips 1 individuated by dicing.

[0064] Stillmore, resin 15 is dripped on the spacings between the LSIchips 1 by means of a dispenser 14 as shown in FIG. 6(d), and thespacings between the LSI chips 1 are filled with protective resin 4 asshown in FIG. 6(e) . After resin 15 is hardened in this condition, theadhesive sheet 12 is diced along boundary lines between the LSI chips 1,and the separate LSI chips 1 having predetermined dimensions can beobtained (FIG. 6(f)). In order to obtain the semiconductor device havingthe structure shown in FIG. 4C, protective resin 6 may be molded on thesides of the bumps 3 in the state shown in FIG. 6(d). In this case, theintermediate electrode 7 may be inserted between the bump 3 and the LSIelectrode 2. The LSI electrode 2 is prevented from being corrodedbecause of moisture absorption by providing protective resin 6 havingnearly the same height as that of the intermediate electrodes 7.

[0065] Hitherto, each of the individuated LSI chips is molded by resinafter it is mounted on a lead frame or a substrate. However, in thestate shown in FIG. 6(d), the steps of resin-coating to dicing areconducted by utilizing the jigs and the tools used at the time ofdicing. That is to say, the steps of handling the individuated LSI chips1 can be eliminated, and there is no necessity for using a metallic moldin the step of molding individuated LSI chip 1. Accordingly, the LSIchip is prevented from being cracked especially at cornered portions,and the number of the steps of using jigs and tools can be reduced.

[0066] The spacings between the LSI chips 1 can be extended not only bythe expanding method shown in FIG. 6 but also by a method that the wafer10 is diced by using a thicker blade than that used in the step shown inFIG. 6(f), in which the LSI chips unified like a wafer are diced afterthe spacings between the LSI chip 1 are coated with protective resin 4.The aforementioned methods may be combined. Although a dicing area canbe minimized according to the expanding method, the advantage of themethod in which the wafer Is diced by using the thick blade is that thewafer can be processed with higher accuracy.

[0067]FIG. 7 shows a method for fabricating semiconductor devices shownin FIGS. 4A,4C in case that thicknesses thereof are made thin.

[0068] Since the steps (a) to (e) shown in FIG. 7 are the same as thoseshown in FIG. 6(a) to (e), the duplicated explanations will be omittedhere. As shown in FIG. 7(d), (e), the spacings between the individuatedLSI chips 1 are coated with protective resin 4. After protective resinis hardened, the LSI chips 1 are unified like a wafer. Then, the unifiedLSI chip 1 are removed from the adhesive sheet 12, and a reverse surfacethereof is grinded as shown in FIG. 7(f), wherein the step of grindingmay be omitted. Next, the LSI chips 1 unified like a wafer are againfixed to the adhesive sheet 12 or the other adhesive sheet, diced alongboundary lines (shown as chain lines in the drawing) between theindividuated LSI chips and separated into the LSI chips (FIG. 7 (g)). Asa result, the semiconductor device shown in FIG. 4A can be obtained.

[0069] According to the method shown in FIG. 7, the thin semiconductordevice can be fabricated by adding the step shown in FIG. 7(f), and oozeand dirt on the reverse surface can be excluded.

[0070] Similarly to the method shown in FIG. 6, the number of the stepsof handling the individuated LSI chips can be eliminated, and there isno necessity for using a metallic mold in the step of resin-molding. Inthis way, the fabrication process of the semiconductor device issimplified. Accordingly, the LSI chip 1 can be prevented from beingcracked, and the number of the steps of using jigs and tools arereduced.

[0071]FIG. 8 shows a method for fabricating a semiconductor device shownin FIG. 5A.

[0072] As shown in FIG. 8(a), intermediate electrodes 7 are previouslyformed on a wafer 7. The wafer 10 sticks to the adhesive sheet 12, anadhesive property of which is decreased by ultraviolet (UV) irradiation.The adhesive sheet 12 which adheres to the wafer 10 is fixed to thefixing ring 11. In this condition, the wafer 10 is diced alongpredetermined lines as shown in FIG. 8(b), and individuated into pluralLSI chips 1. Next, after an expanding jig 13 is situated at apredetermined position which is near and lower than the fixing ring 11as shown in FIG. 8(c), the expanding jig 13 is pushed up to expand theadhesive sheet 12, and spacings between the LSI chips 1 are extended.

[0073] Moreover, as shown in FIG. 8(d), liquid resin 15 is dripped onthe intermediate electrodes 7 as well as the spacings between the LSIchips 1 by means of a dispenser 14 so that the intermediate electrodes 7are coated with protective resin 4,6. After protective resin 4,6 arehardened, the LSI chips 1 unified like a wafer are removed from theadhesive sheet 12 as shown in FIG. 8(e), and the obverse surface of theunified LSI chips 1 is grinded to expose the intermediate electrodes 7as shown in FIG. 8(f). In this case, the reverse surface of the unifiedLSI chips 1 may be grined also at need, and thereby the thickness of thesemiconductor devices are determined. Subsequently, bumps 3 arerespectively mounted on top surfaces of the intermediate electrodes 7 asshown in FIG. 8(g). Moreover, the unified LSI chips 1 on which the bumps3 are mounted are fixed to the adhesive sheet 12, and diced along theboundary lines (shown as chain lines in the drawing) between theindividuated LSI chips 1 coated with protective resin 4,6 into theseparate chips having predetermined dimensions as shown in FIG. 8(h).

[0074] According to the method for fabricating the semiconductor deviceshown in FIG. 8, protective resin 4,6 are coated collectively, and thethin semiconductor device provided with the intermediate electrodes 7buried in resin can be fabricated easily. Moreover, semiprocessed goodscan be handled as if a wafer throughout the almost whole fabricationprocess, and jigs necessary for operating the fixing ring can be whollyused as the jigs and the tools at the time of fabrication.

[0075] Accordingly, the thin semiconductor device provided with theintermediate electrodes 7 which contribute to the improvement ofreliability of the semiconductor device can be fabricated in the lumpaccording to the aforementioned method. Moreover, since there is nonecessity for using a metallic mold which has been necessary in theconventional fabrication process at the time of transfer molding, aprovision for fabricating the semiconductor device can be simplified,and the semiconductor device having almost the same dimensions as thoseof the LSI chip can be fabricated.

[0076]FIG. 9 shows a method for fabricating a semiconductor device shownin FIG. 4D.

[0077] Since the steps shown in FIG. 9(a) to (e) are the same as thoseshown in FIG. 7(a) to (e), duplicated explanations will be omitted here.After resin is hardened in the step shown in FIG. 9(e), the unified LSIchips 1 are removed from the adhesive sheet 12, the unified LSI chips 1are turned over, the reverse surface of the unified chips 1 is coatedwith resin 15 by means of a dispenser 14, and thereby protective resin 5is formed thereon (FIG. 9(f)). After protective resin 6 is hardened, thesurface is grined. Next, as shown in FIG. 9(g), the unified LSI chips 1are again fixed to the adhesive sheet 12 or the other adhesive sheet,and diced along boundary lines (shown as chain lines in the drawing)between the individuated LSI chips 1 as shown in FIG. 9(g) Then, thesemiconductor device shown in FIG. 4D is completed.

[0078] As mentioned in the above, since protective resin 4,5,6 areprovided for the whole surfaces of the LSI chip 1 by a simplefabrication process, there is no necessity for using a metallic moldwhich has been necessary in the conventional method at the step oftransfer molding. The provision for fabricating the semiconductor devicecan be simplified, and the semiconductor device having almost the sameexternal dimensions as those of the LSI chip can be fabricated. Althoughresin is applied to the reverse surface of the LSI chip by means of adispenser in the above explanations, other method for applying resin,such as spin coating, screen printing, roller application, showering,application by resin sheet, etc. may be adopted.

[0079]FIG. 10 shows a method for fabricating the semiconductor deviceshown in FIG. 5B. Since the steps shown in FIG. 10(a) to (f) are thesame as those shown in FIG. 8(a) to (f), duplicated explanations will beomitted here. After the step of grinding the unified LSI chips shown inFIG. 10(f) is conducted, the reverse surface of the unified LSI chips,which is opposite to the other surface mounting the intermediateelectrodes 7 thereon, is coated with protective resin 5 as shown in FIG.10(g) . Subsequently, the bumps 3 are respectively mounted on theintermediate electrodes 7 as shown in FIG. 10(h) . Thereafter, theunified LSI chips on which the bumps 3 have been mounted are again fixedto the adhesive sheet 12 or the other sheet, and diced into the separateLSI chips 1 along the boundary lines (the chain lines in the drawing)between the LSI chips as shown in FIG. 10(i). Since the method forfabricating the semiconductor device shown in FIG. 10 includes the stepshown as (f), the thin semiconductor device can be fabricated, and oozeand dirt caused by resin can be excluded.

[0080] According to the method shown in FIG. 10, protective resin 4,6can be provided for the LSI chip 1 in the lump. Moreover, since thebumps 3 is mounted on the intermediate electrode 7 buried in resin,stress exerted on a joint between the bump 3 and the chip (not shown) isreduced, and the bumps 3 is prevented for being covered with protectiveresin 6. Stillmore, semiprocessed goods are handled as if waferthroughout almost the whole fabrication process, and all the jigs usedin the step of fixing the rings can be used at the time of fabrication.Accordingly, the thin semiconductor device having improved reliabilityin jointing can be fabricated in the lump. Moreover, since semiprocessedgoods can be handled as if a wafer in the aforementioned process,investment in the provision for fabricating the semiconductor device canbe cut down, the jigs and the tools can be simplified, and cost of thesemiconductor device can be reduced. The bumps can be formed by solderpaste-printing and reflow soldering. The same purpose can be attained bysolder ball-mounting, plating or evaporation.

[0081]FIG. 11 shows a modification of the method shown in FIG. 9. Thefeature of this embodiment of the invention is that the reverse surfaceof the wafer is coated with resin before the wafer is fixed to theadhesive sheet dissimilarly to the other method in which the reversesurface is coated with resin after grinding.

[0082] As shown in FIG. 11(a), the reverse surface of the wafer 10, onwhich the bumps 3 are provided previously, is coated with resin 15 bymeans of a dispenser 14 to from a protective resin 5 in the first place.Although the dispenser 14 is used in the above explanation, any one ofspin coating, screen printing, roller application, showering,application using a resin sheet, etc. may be adopted. Next, as shown inFIG. 11(b), the reverse surface of the wafer 10 on which protectiveresin 5 is coated is fixed to the adhesive sheet 12, to which the fixingring 11 is fixed. Then, the wafer 10 is so diced that the adhesive sheet12 is not diced, and individuated into the LSI chips 1 as shown in FIG.11(c) . Next, the expanding jig 13 which is situated in the inside ofand lower than the fixing ring 11 is pushed up to expand the adhesivesheet 12 and extend the spacing between the LSI chips 1 as shown in FIG.11(d). The spacings between the LSI chips 1 formed in this way arecoated with resin 15 which is dripped from the dispenser 14 to formprotective resin 4 as shown in FIG. 11(e). After protective resin 4 isdried in this condition as shown in FIG. 11(f), the LSI chips 1 unifiedlike a wafer are removed from the adhesive sheet 12, turned over, andfixed to the adhesive sheet 12. Then, the reverse surface coated withprotective resin 5 is grined as shown in FIG. 11(g). Thereafter, theunified LSI chips 1 are diced along the boundary lines between the LSIchips 1, and the separate LSI chips 1 can be obtained. The effect ofthis embodiment is the same as that shown in FIG. 9.

[0083] Finally, reliability of the semiconductor device according to theinvention shown in FIG. 4A is compared with that of the conventionalsemiconductor device (the bare chip) shown in FIG. 1, supposing acondition that the semiconductor devices are packed up and transported.In case that protective resin 4 is removed from the semiconductor deviceshown in FIG. 4A, a permissible width (corresponding to a permissiblearea 107 shown in FIG. 1) of the LSI chip is 25 μm. The permissiblewidth of the semiconductor device shown in FIG. 4A is defined as the sumof 25 μm and the thickness of protective resin 4.

[0084] Explaining concretely, the LSI chips under a test are containedin trays and packed up together with shock-absorbing members. A droppingtest is performed on the package of the semiconductor devices from aheight of 0.7 mm. Moreover, the semiconductor device is transferred froma tray to another tray using a pincette supposing the worst conditionthat the semiconductor devices are mounted on the printed circuit boardby the user.

[0085]FIG. 12 shows relations between the permissible widths of thesemiconductor devices and percent detectives of the semiconductordevices. A graph represented by black circles and segments of linesshows data of the semiconductor devices according to the invention shownin FIG. 4A, and another graph comprising white circles shows data of theconventional semiconductor device shown in FIG. 1. As shown in FIG. 12,the percent defective of the semiconductor device according to theinvention shown in FIG. 4A decreases and yield rate of the sameincreases sharply as the permissible width increases. When thepermissible width is more than 100 μm, the effect of the inventionbecomes further noticeable, that is to say , the semiconductor deviceaccording to the invention is far more excellent in the percentagedetective and mechanical reliability than the conventional semiconductordevice having the same dimensions.

[0086] In the semiconductor device submitted to the aforementioned test,although protective resin 4 is formed by potting, lattice-shaped sheetswhich are formed of resin and prepared previously may be insertedbetween the LSI chips, or the LSI chip may be covered with athermocontracting film. Moreover, protective resin 4,5, 6may be replacedwith rubber, elastomer, etc.

[0087] In the embodiments shown in FIGS. 7,9 although the wafer is dicedafter the reverse surface thereof is coated with protective resin andgrinded, the wafer may be diced before the reverse surface is grinded.In this case, the reverse surfaces of the LSI chips are grinded in acondition that the bump-mounting surfaces of the LSI chips are stuck tothe adhesive sheet.

[0088] Although it is simple to conduct the steps of applying resin tothe reverse surface, grinding the reverse surface, forming the bumps,etc. before the wafer is separated into the LSI chips, these steps maybe conducted after the wafer is separated into the LSI chips, ifrestrictions are interposed on the provision for fabricatingsemiconductor device.

[0089] Although the wafer is diced after the reverse surface, which hasbeen coated with resin, is grinded in the embodiments shown in FIGS.7,9, the wafer may be diced before the reverse surface is grinded. Inthis case, the reverse surfaces of the LSI chips are grinded in a statethat the surfaces of the LSI chips, on which the bumps have formed, arestuck to the adhesive sheet.

[0090] As mentioned in the above, according to the semiconductor deviceaccording to the invention, since the chip is prevented from beingdamaged by providing protective members at least for the side surfacesof the bare chip, defects occurring at the time of transportation ormounting, or imperfections in a joint occurring at the time of mountingcan be reduced, and reliability and yield rate of the products can beimproved. Moreover, since the main part of the semiconductor device isthe bare chip basically, there is no necessity for using interposeretc., and the number of parts or the step of the fabrication process canbe reduced, hence cost of the semiconductor device can be cut down, thesemiconductor device can be small-sized, and reliability of thesemiconductor device can be improved.

[0091] Moreover, according to the method for fabricating thesemiconductor device according to the invention, since the methodcomprises the steps of sticking the wafer on which plural bumps areformed to the adhesive sheet, fixing the periphery of the adhesive sheetto the fixing ring, dicing the wafer into the individuated chips,forming the spacings between the individuated chips by expanding theadhesive sheet at positions where the individuated chips adhere to theadhesive sheet, coating the spacings between the individuated chips withresin, hardening resin, and dicing the chips unified like a wafer at thespacings between the individuated chips, the separate chips do not passthrough the fabrication process, the steps of handling the chips can beeliminated, the number of the steps in which the jigs and the tools areused is reduced, and the metallic mold becomes unnecessary in the stepsmolding resin, hence the investment for the provision and fabricatingcost can be cut down. Moreover, since the LSI chip is prevented frombeing cracked by providing protective resin for the side surfaces of theLSI chip, reliability and yield rate of the semiconductor device areheightened.

[0092] Moreover, according to the other method for fabricating thesemiconductor device, since the other method comprises the steps ofsticking the wafer on which the intermediate electrodes for mounting thebumps are formed to the adhesive sheet, fixing the periphery of theadhesive sheet to the fixing ring, dicing the wafer into individuatedchips, forming the spacings between the individuated chips by expandingthe adhesive sheet, coating the spacings and the surfaces on which theintermediate electrodes are formed with resin, hardening resin, removingthe chips unified like a wafer by hardening of resin from the adhesivesheet, grinding the surface of the unified chips till the intermediateelectrodes are exposed, mounting the bumps on the grinded intermediateelectrodes, sticking the unified chips to the adhesive sheet, and dicingthe unified chips along boundary lines between the individuated chips,the separate chips do not pass through the fabrication process, thesteps of handling the separate chips is eliminated, the number of thesteps of using jigs and tools is reduced, the metallic mold becomesunnecessary in the step of molding resin , and the investment for theprovision and fabrication cost can be reduced. Moreover, since the LSIchips are prevented from being cracked by providing protective resin forthe side surfaces and the electrode-mounting surface of the LSI chip,reliability and yield rate of the semiconductor device can beheightened.

[0093] Although the invention has been described with respect tospecific embodiment for complete and clear disclosure, the appendedclaims are not to be thus limited but are to be construed as embodyingall modification and alternative constructions that may be occurred toone skilled in the art which fairly fall within the basic teaching hereis set forth.

[0094] What is claimed is:

1. A semiconductor device, comprising: a bare chip fabricated as a largescale integrated circuit, plural bumps provided for an obverse surfaceof said bare chip, and protective members formed on at least sidesurfaces of said bare chip.
 2. A semiconductor device according to claim1 , wherein: said protective member is formed on said obverse surface onwhich said plural bumps are formed in addition to said side surfaces. 3.A semiconductor device according to claim 1 , wherein: said protectivemember is formed on a reverse surface of said bare chip in addition tosaid side surfaces.
 4. A semiconductor device according to claim 1 ,wherein: said protective member is formed of resin.
 5. A semiconductordevice according to claim 1 , wherein: said bare chip is provided withintermediate electrodes inserted between electrodes connected withcircuit patterns of said bare chip and said bumps.
 6. A method forfabricating a semiconductor device, comprising the steps of: sticking awafer on which plural bumps are formed to an adhesive sheet, dicing saidwafer into individuated chips so as not to dice said adhesive sheet,forming spacings having predetermined widths between said individuatedchips stuck to said adhesive sheet, coating said spacings formed betweensaid individuated chips with resin, hardening said resin to unify saidindividuated chips like a wafer, and providing separate chips by dicingsaid unified chips along boundary lines between said individuated chips.7. A method for fabricating a semiconductor device according to claim 6, wherein: said step of coating said resin comprises the step of coatinga surface on which said bumps are formed with said resin.
 8. A method for fabricating a semiconductor device according to claim 6 , wherein:said step of coating said resin comprises the step of coating a reversesurface of said unified chips with said resin.
 9. A method forfabricating a semiconductor device according to claim 6 , wherein: saidstep of sticking said wafer to said adhesive sheet comprises the step ofapplying said resin to a reverse surface of said wafer as a prior stepthereof.
 10. A method for fabricating a semiconductor device accordingto claim 6 , wherein: said step of providing separate chips comprisesthe step of grinding a reverse surface of said unified chips or saidseparate chip.
 11. A method for fabricating a semiconductor deviceaccording to claim 6 , wherein: said step of providing separate chipscomprises the steps of: grinding a reverse surface of said unifiedchips, and coating said reverse surface of said unified chips or saidseparate chip with said resin.
 12. A method for fabricating asemiconductor device according to claim 6 , wherein: said steps offorming said spacings having predetermined widths between saidindividuated chips comprises the steps of: fixing said adhesive sheet toa fixing member at a periphery of said adhesive sheet, and pushing upsaid adhesive sheet in a neighborhood of said fixing member by means ofan expanding jig to expand an area of said adhesive sheet to which saidindividuated chips are stuck.
 13. A method for fabricating asemiconductor device according to claim 6 , wherein: said steps offorming said spacings having predetermined widths between saidindividuated chips comprises the step of dicing said wafer into saidindividuated chips by using a thicker blade than that used in case thatsaid adhesive sheet coated with said resin is diced.
 14. A method forfabricating a semiconductor device, comprising the steps of: sticking awafer on which intermediate electrodes for mounting bumps thereon arearranged in accordance with a circuit pattern to an adhesive sheet,dicing said wafer into individuated chips so as not to dice saidadhesive sheet, forming spacings between said individuated chips stuckto said adhesive sheet, coating said spacings formed between saidindividuated chips and a surface of said wafer on which saidintermediated electrodes are arranged with resin, hardening said resinto unify said individuated chips like a wafer, grinding an obversesurface of said unified chips to expose said intermediate electrodes,and providing separate chips by dicing said unified chips along boundarylines between said individuated chips.
 15. A method for fabricating asemiconductor device according to claim 14 , wherein: said step ofgrinding said obverse surface of said unified chips comprises the stepof respectively mounting said plural bumps on surfaces of said grindedintermediate electrodes.
 16. A method for fabricating a semiconductordevice according to claim 14 , wherein: said step of providing saidseparate chips comprises the step of respectively mounting plural bumpson said separated intermediate electrodes.
 17. A method for fabricatinga semiconductor device according to claim 14 , wherein: said step ofgrinding an obverse surface of said unified chips comprises the step ofcoating a reverse surface of said unified chips with said resin.
 18. Amethod for fabricating a semiconductor device according to claim 14 ,wherein: said step of sticking said wafer to said adhesive sheetcomprises the step of coating a reverse surface of said wafer with saidresin as a prior step thereof.
 19. A method for fabricating asemiconductor device according to claim 14 , wherein: said step ofproviding said separate chips comprises the step of grinding a reversesurface of said unified chips or said separate chip.
 20. A method forfabricating a semiconductor device according to claim 14 , wherein: saidstep of providing separate chips comprises the steps of: grinding areverse surface of said unified chips, and coating said reverse surfaceof said unified chips or said separate chip.
 21. A method forfabricating a semiconductor device according to claim 14 , wherein: saidsteps of forming said spacings between said individuated chips comprisesthe steps of: fixing said adhesive sheet to a fixing member at peripheryof said adhesive sheet, and pushing up said adhesive sheet in aneighborhood of said fixing member by means of an expanding jig toexpand and area of said adhesive sheet to which said individuated chipsare stuck.
 22. A method for fabricating a semiconductor device accordingto claim 14 , wherein: said step forming said spacings between saidindividuated chips comprises step of dicing said wafer into individuatedchips by using a thicker blade than that used in case that said adhesivesheet coated with said resin is diced.